Extraordinary interactions between rare false killer whales and bottlenose dolphins have been captured by the team behind Blue Planet II.
Once thought of as enemies, these two species of dolphin are in fact best friends for life.
They are six metres long, weigh over a tonne and are a relative of the orca, but very little is known about the false killer whale (Pseudorca crassidens). Now, filmed extensively for the first time, Blue Planet II has given audiences an insight into the previously unknown world of these elusive ocean dwellers.
Sarah Conner, assistant producer, directed much of the false killer whale filming featured in the programme.
“I have to say it was amazing seeing the false killer whales and the bottlenosed dolphins make such a clear formation from the air, we were actually speechless up there,” she says.
The crew made use of a towcam (a camera towed behind the boat) allowing them to travel fast enough to keep up with their speedy subjects.
“It was funny as the bottlenosed dolphins would come up to have a good look at it, but the false killer whales were a bit more shy and it took them a little longer before they'd come close,” says Conner.
Like their orca cousins, false killer whales are actually dolphins and we now know they gather together in great numbers off the coast of New Zealand with groups of bottlenose dolphins.
Conner says normally when ceteceans are seen spending time together it is a coincidental meeting around feeding such as orca and humpbacks feeding together on herring in Norway.
“More like meeting in a supermarket or a place of work,” she adds.
What makes the false killer whale/bottlenosed dolphin relationship off the coast of New Zealand different from other cetacean interactions, explains Conner, is that the species have not only been seen hunting together, but also socialising, travelling and resting together over long periods of time (sometimes years) and over long distances.
“It’s more than just a single moment like feeding on a school of fish; it’s more like wanting to spend time with your friends, so you would get a takeaway and eat together. But you'd also go for walks together, go to the cinema, have sleep-overs and generally hang around together,” says Conner.
Marine biologist Jochen Zaeschmar has studied false killer whales for 17 years. Until now he has relied on anecdotal sightings for his encounters with the dolphins.
“We have 800km of coastline. Finding them is like looking for a needle in a haystack,” he says.
Working with the Blue Planet II team allowed for aerial surveys to locate the false killer whales far more easily.
Zaeschmar taught local whale watchers to tell the difference between false killer whales and the similar looking pilot whale and used their sightings and historic sighting data to find a starting point for the search.
Filming this gathering allowed the group to be studied: over 150 false killer whales and around 1000 bottlenose dolphins were recorded from the air enabling Zaeschmar and the team to witness the group bonding. It was the first time Zaeschmar had seen the gathering from above rather than his usual view from the deck of a boat.
This aerial footage allowed Zaeschmar to count all of the false killer whales of New Zealand for the first time.
“He can now monitor the population each year to see how the numbers and indivduals are surviving out in the high seas and with fisheries interactions,” says Conner.
Zaeschmar made some ground-breaking discoveries; until now the species were thought to be deep ocean dwellers, occasionally visiting shallow waters. It is now believed they spend six months in shallow waters around New Zealand, and six months in deeper water with the same individuals making frequent visits to the coast. Zaeschmar now believes that they are part-time residents.
“They’re part of our New Zealand mega-fauna. Real locals. And they need protecting,” he says. Currently, false killer whale population studies are few and far between, but where data has been collected it is clear that the species is under threat.
The footage and accompanying knowledge gathered by the Blue Planet II team has generated the necessary interest to secure more backing for future research. Zaeschmar wants to study further their ecology and the relationship between false killer whales and the bottlenose dolphins in order to understand the species.
#OurBluePlanet is a collaboration between BBC Earth and Alucia Productions.
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